[FFmpeg-devel] [PATCH 2/3] lavf/utils: add flag to discard timestamps on corrupted frames
Michael Niedermayer
michael at niedermayer.cc
Wed Dec 13 14:52:00 EET 2017
On Wed, Dec 13, 2017 at 03:04:06AM -0600, Rodger Combs wrote:
>
>
> > On Dec 10, 2017, at 09:27, Michael Niedermayer <michael at niedermayer.cc> wrote:
> >
> > On Sun, Dec 10, 2017 at 05:17:44AM -0600, Rodger Combs wrote:
> >>
> >>
> >>> On Dec 9, 2017, at 12:19, Michael Niedermayer <michael at niedermayer.cc> wrote:
> >>>
> >>> On Fri, Dec 08, 2017 at 10:34:39PM -0600, Rodger Combs wrote:
> >>>>
> >>>>
> >>>>> On Dec 8, 2017, at 11:06, Michael Niedermayer <michael at niedermayer.cc> wrote:
> >>>>>
> >>>>> On Thu, Dec 07, 2017 at 10:23:15PM -0600, Rodger Combs wrote:
> >>>>>> ---
> >>>>>> libavformat/avformat.h | 1 +
> >>>>>> libavformat/options_table.h | 1 +
> >>>>>> libavformat/utils.c | 8 ++++++++
> >>>>>> 3 files changed, 10 insertions(+)
> >>>>>>
> >>>>>> diff --git a/libavformat/avformat.h b/libavformat/avformat.h
> >>>>>> index 4f2798a871..d10d583dff 100644
> >>>>>> --- a/libavformat/avformat.h
> >>>>>> +++ b/libavformat/avformat.h
> >>>>>> @@ -1450,6 +1450,7 @@ typedef struct AVFormatContext {
> >>>>>> #define AVFMT_FLAG_FAST_SEEK 0x80000 ///< Enable fast, but inaccurate seeks for some formats
> >>>>>> #define AVFMT_FLAG_SHORTEST 0x100000 ///< Stop muxing when the shortest stream stops.
> >>>>>> #define AVFMT_FLAG_AUTO_BSF 0x200000 ///< Add bitstream filters as requested by the muxer
> >>>>>> +#define AVFMT_FLAG_DISCARD_CORRUPT_TS 0x400000 ///< Discard timestamps of frames marked corrupt
> >>>>>>
> >>>>>> /**
> >>>>>> * Maximum size of the data read from input for determining
> >>>>>> diff --git a/libavformat/options_table.h b/libavformat/options_table.h
> >>>>>> index b8fa47c6fd..515574d3e0 100644
> >>>>>> --- a/libavformat/options_table.h
> >>>>>> +++ b/libavformat/options_table.h
> >>>>>> @@ -58,6 +58,7 @@ static const AVOption avformat_options[] = {
> >>>>>> {"bitexact", "do not write random/volatile data", 0, AV_OPT_TYPE_CONST, { .i64 = AVFMT_FLAG_BITEXACT }, 0, 0, E, "fflags" },
> >>>>>> {"shortest", "stop muxing with the shortest stream", 0, AV_OPT_TYPE_CONST, { .i64 = AVFMT_FLAG_SHORTEST }, 0, 0, E, "fflags" },
> >>>>>> {"autobsf", "add needed bsfs automatically", 0, AV_OPT_TYPE_CONST, { .i64 = AVFMT_FLAG_AUTO_BSF }, 0, 0, E, "fflags" },
> >>>>>> +{"discardcorruptts", "discard timestamps on corrupted frames", 0, AV_OPT_TYPE_CONST, { .i64 = AVFMT_FLAG_DISCARD_CORRUPT_TS }, 0, 0, E, "fflags" },
> >>>>>> {"analyzeduration", "specify how many microseconds are analyzed to probe the input", OFFSET(max_analyze_duration), AV_OPT_TYPE_INT64, {.i64 = 0 }, 0, INT64_MAX, D},
> >>>>>> {"cryptokey", "decryption key", OFFSET(key), AV_OPT_TYPE_BINARY, {.dbl = 0}, 0, 0, D},
> >>>>>> {"indexmem", "max memory used for timestamp index (per stream)", OFFSET(max_index_size), AV_OPT_TYPE_INT, {.i64 = 1<<20 }, 0, INT_MAX, D},
> >>>>>> diff --git a/libavformat/utils.c b/libavformat/utils.c
> >>>>>> index 84e49208b8..98af941e9f 100644
> >>>>>> --- a/libavformat/utils.c
> >>>>>> +++ b/libavformat/utils.c
> >>>>>
> >>>>>> @@ -873,6 +873,14 @@ int ff_read_packet(AVFormatContext *s, AVPacket *pkt)
> >>>>>> st->cur_dts = wrap_timestamp(st, st->cur_dts);
> >>>>>> }
> >>>>>>
> >>>>>> + if ((s->flags & AVFMT_FLAG_DISCARD_CORRUPT_TS) &&
> >>>>>> + (pkt->flags & AV_PKT_FLAG_CORRUPT)) {
> >>>>>> + pkt->pts = pkt->dts = AV_NOPTS_VALUE;
> >>>>>> + av_log(s, AV_LOG_WARNING,
> >>>>>> + "Discarded timestamp on corrupted packet (stream = %d)\n",
> >>>>>> + pkt->stream_index);
> >>>>>> + }
> >>>>>
> >>>>> how many of the cases that set AV_PKT_FLAG_CORRUPT can even be due to
> >>>>> the timestamp ?
> >>>>
> >>>> Pretty much just the new TEI check, or potentially other CRC checks. I don't _think_ the continuity-counter check failing could indicate an incorrect timestamp. I suppose we could add a second flag just for corruption that could affect timestamps?
> >>>
> >>> I think thats a great idea, maybe if we already change it we should
> >>> also split the truncated case out as it is very common.
> >>>
> >>> AV_PKT_FLAG_DATA_CORRUPT // the packet data may be corrupted
> >>> AV_PKT_FLAG_DATA_TRUNCATED // the packet size may be corrupted, data available is undamaged unless another flag indicates otherwise. Any headers or sub-packets which are complete are non corrupted-
> >>> AV_PKT_FLAG_TS_CORRUPT // the packets timestamps and or duration may be corrupted
> >>>
> >>> #define AV_PKT_FLAG_CORRUPT (AV_PKT_FLAG_DATA_CORRUPT | AV_PKT_FLAG_DATA_TRUNCATED | AV_PKT_FLAG_TS_CORRUPT)
> >>
> >> What kind of API bump would be needed to make this kind of change?
> >
> > IIUC we are still within the major bump thing (didnt check but others
> > have said it in relation to other changes)
> >
> > a minor bump should probably be done anyway to signal that these
> > additional flag may be set in the output
>
> Come to think of it, I think a major bump would be required, as this would break ABI (applications checking for AV_PKT_FLAG_CORRUPT would need to be rebuilt to handle anything that sets AV_PKT_FLAG_DATA_CORRUPT or the others).
yes of couse, thats why i talked about still being in the major bump
API/ABI unstability period above
If one wants to add these flags in a ABI compatible way, that can be
done but its more messy, one can just add the new flags as independant
new flags
#define AV_PKT_FLAG_CORRUPT 0x0002 (unchanged)
#define AV_PKT_FLAG_DATA_CORRUPT 0x0020
#define AV_PKT_FLAG_DATA_TRUNCATED 0x0040
#define AV_PKT_FLAG_TS_CORRUPT 0x0080
then to set one in the new code, code like this would be used
flags |= AV_PKT_FLAG_CORRUPT | AV_PKT_FLAG_DATA_CORRUPT
this is compatible with the old code
to check code like this would be needed
tmp = flags & 0x00E2
if (tmp == AV_PKT_FLAG_CORRUPT || (tmp&AV_PKT_FLAG_DATA_CORRUPT))
to support both the old style and new more specific style
i dont think we need this though as we are quite close to the last
ABI bump
[...]
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